Diseases of the immune systems pose a major threat due to the potentially devastating effects that such diseases have on humanity. One class of diseases related to the immune system are immuno-allergical diseases. Immuno-allergical diseases are a major cause of concern, and much research is being conducted in order to develop potent compounds that will be effective in treating such diseases. Allergy is a state of hypersensitivity induced by exposure to a particular antigen (allergen) resulting in harmful immunologic reaction on subsequent exposures. An example of an immuno-allergical disease is allergic rhinitis (hay fever). Allergic rhinitis is a common immuno-allergic condition that affects one in every five Americans. Over one billion dollars is spent each year in the U.S. to treat this condition. Sneezing, nasal congestion, and eye irritation are some of the symptoms of allergic rhinitis. Another example of an immuno-allergical disease is bronchial asthma—a breathing problem that results from spasm (bronchospasm) of the muscles surrounding the walls of the lung airways (bronchi). Allergic asthma is the most common type of asthma, typically first appearing in childhood.
Another example of an immuno-allergical disease is psoriasis, which is a chronic skin disease characterized by scaling and inflammation, and it affects 1.5 to 2 percent of the United States population, or almost 5 million people. It occurs in all age groups and about equally in men and women. People with psoriasis may suffer discomfort, restricted motion of joints, and emotional distress.
Another type of immuno-allergical disease is Crohn's disease, which is a chronic inflammatory disease of the intestines. It primarily causes ulceration in the small and large intestines but can affect the digestive system anywhere between the mouth and the anus. The disease is found in equal frequency in men and women, and it usually affects young patients in their teens or early twenties. Once the disease begins, it tends to be a chronic, recurrent condition with periods of remission and disease exacerbation.
A third class of diseases related to the immune system are autoimmune diseases. Autoimmune diseases are illnesses that occur when the body's tissues are attacked by its own immune system. The immune system is a complex organization within the body that is designed normally to seek and destroy invaders of the body, particularly infections. Patients with these diseases have unusual antibodies in their blood that target their own body tissues. An example of an autoimmune disease is systemic lupus erythematosus. Lupus is a chronic inflammatory condition, caused by autoimmune disease, which causes disease of the skin, heart, lungs, kidneys, joints, and nervous system. When internal organs are involved, the condition is called systemic lupus erythematosus. Another type of an autoimmune disease is autoimmune thyroiditis, which is an autoimmune disease of the thyroid. Another type of autoimmune disease is rheumatoid arthritis, which causes chronic inflammation of the joints, the tissue around the joints, as well as other organs in the body.
Another example of an autoimmune system is experimental autoimmune encephalomyelitis (EAE). EAE is an inflammatory condition of the central nervous system, which is the murine equivalent to multiple sclerosis.
A forth class of conditions related to the immune system is organ or tissue rejection following transplantation. Organ or tissue rejection is a major complication occurring in patients who have undergone transplantation. For example, chronic graft-versus-host disease (cGvHD), a major complication occurring in patients post-allogeneic bone marrow transplantation, is believed to be the result of an autoimmune-like process mediated by immunocompetent T-cells. Chronic GvHD often results in sclerodermoid-fibrotic skin lesions [see, e.g., Chosidow et al., Sclerodermatous chronic graft-versus-host disease. analysis of seven cases. J Am Acad Dermatol 26:49-53, 1992]. Other examples of organ or tissue rejection following transplantation include skin graft rejection and cardiac graft rejection.
Autoimmune diseases and immuno-allergical diseases pose a major problem to society. Organ or tissue rejection following transplantation presents another problem that severely limits the use and application of tissue and organ transplantation in medicine.